The invention relates to an apparatus for the preparation of thermoplastic plastics material to be recycled, with at least two treatment stages—following one after the other with respect to the flow of material—for the material, in which in each stage the material is introduced into a receiving container from above and is heated and mixed, and optionally also crushed, in the receiving container by rotating tools, and the material treated in this way is discharged from the respective receiving container by means of a discharge member, preferably by means of at least one screw. In addition, the invention relates to a method of preparing thermoplastic plastics material to be recycled, using an apparatus defined in the introduction.
An apparatus of the type described in the introduction is known (AT 411235 B). In the case of a known apparatus of this type, a continuous flow of material takes place through the two receiving containers which are arranged in series and are under vacuum. In this way, a recycled plastics-material product of adequate quality can be obtained in most cases. In the field of foodstuffs packaging, in particular drinks bottles, however, particularly high demands are made with respect to the decontamination of the plastics material treated. The quality of the decontamination depends upon the vacuum and temperature conditions prevailing during the treatment and, in particular, upon the dwell period which the individual particles of plastics material spend in the receiving container. Investigations have shown that in the case of the continuous process mentioned above the period which the individual particles of plastics material spend in the receiving container. Investigations have shown that in the case of the continuous process mentioned above the said dwell period can be of widely differing duration, depending upon whether the particles of material being treated or a plurality of such particles spend a relatively long time in the receiving container before they are removed from it by the screw, or whether individual particles of material succeed in leaving the receiving container relatively quickly again after being introduced into the said receiving container.